ermm i need help with factorising quadratics and quadratic sequences i tried to understand it but i cant can someone help me with this?

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i keep getting confused with the squared part and the other part my exam is in june and i really want to get an a

Posted Tue 31st May, 2011 @ 22:18 by Stephanie

6 Answers

  • 1 vote

alright thanks guys :))x

i will look at them now :D

Answered Wed 1st June, 2011 @ 13:57 by Stephanie
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FACTORISING A QUADRATIC MEANS PUTTING INTO 2 BRACKETS

1.     THE STANDARD FORMAT FOR A QUADRATIC EQUATION IS: ax² + bx + c    e.g x² + 3x + 2 = 0²

2.     FACTORISING METHOD WHEN “a=1”

3.     ALWAYS REARRANGE INTO THE STANDARD FORMAT: “ax² + bx + c = 0”

4.     WRITE DOWN THE 2 BRACKETS WITH THE x’s IN: (x     )(x     )=0

5.     THEN FIND 2 NUMBERS THAT MULTIPY TO GIVE “c” BUT ALSO ADD/SUBTRACT TO GIVE “b”

6.     PUT THEM IN THE BRACKETS AND CHECK THAT THE SIGNS WORK PROPERLY OTHERWISE YOU WILL GET THE WRONG ANSWER

7.     TO CHECK YOUR ANSWER EXPAND THE 2 BRACKETS TO SEE IF YOU HAVE MATCHING ANSWERS TO THE QUADRATIC EQUATION!

WHEN a DOES NOT =1

E.G SOLVE 3x² + 7x=6 BY FACTORISING

1.     REARRANGE IT TO THE STANDARD FORMAT

2.     THEN BECAUSE a = 3 THE 2 x TERMS WILL HAVE TO MULTIPLY TO GIVE 3x² SO THE BRACKETS WILL BE: (3x    )(x     )=0

3.     NOW LOOK AT ALL THE PAIRS OF NUMBERS THAT WILL MULTIPLY WITH EACH OTHER TO GIVE c AND ADD/SUBTRACT TO GIVE b SO EITHER 1 X 6 OR 2 X 3

4.     NOW TRY ALL THE POSSIBILITIES IN THE BRACKETS AND ELIMINATE WHICH EVER ONES YOU DON’T NEED.

5.     (3x   1)(x    6) multiplies to give 18x & 1x which also add/subtract to give 17x or 19x

6.     (3x   6)(X    1) multiplies to give 3x & 6x which also add/subtract to give 9x or 3x

7.     (3x   3)(x    2) multiplies to give 6x & 3x which also add/subtract to give 9x or 3x

8.     (3x   2)(x    3) multiplies to give 9x & 2x which also add/subtract to give 11x 0r 7x

9.     So (3x   2)(x    3) is the combination that gives b=7

10.  Now fill in the +/- signs so that the combination adds up to +7 so that brackets are (3x -  2)(x  +  3)

11.  To check expand the brackets to see if you end up with the original equation!

 HOPE THIS HELPS:D

Answered Tue 31st May, 2011 @ 23:05 by SONIKA
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aww thanks that really helped :))x i need to learn this!

Answered Tue 31st May, 2011 @ 23:22 by Stephanie
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Easier way is look at my videos that teach you this!

Answered Wed 1st June, 2011 @ 00:47 by Star Pupils Tuition
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i've got a couple of resources on this if that's going to help you :) ** 

Answered Wed 1st June, 2011 @ 08:11 by Kelly:)
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IVE GOT AN AMAZING! POWERPOINT ON MANIPULATING QUADRATICS!!!

Answered Wed 1st June, 2011 @ 12:47 by Georgina